Laura Erickson's For the Birds

Monday, November 13, 2017

Frankie, the St. Louis County owl

Frankie the St. Louis County Northern Saw-whet Owl
Photo by Pat Lueders.

Last Tuesday night, just when I was heading to bed, my good friend Susan sent me a text message. Like me, Susan lives in St. Louis County, but unlike mine up here in Minnesota, her St. Louis County is in Missouri, where for many years she’s been active with the World Bird Sanctuary, helping with bird banding.

The owl-banding program there is fairly new—it started in 2012 as an experiment. No one could be sure if they'd catch any owls at all based on how few birders report Saw-whet Owls in that area. But on the first night, the very first time they checked their nets, there was a Northern Saw-whet Owl! They don’t capture as many as we do at migration points along the Great Lakes, especially at Hawk Ridge, but their banding program has proven to be a wonderful success. A few nights ago, they extracted owls from the nets 7 times, capturing five different individuals—two of them got caught a second time. Every year between October and early December they catch between 8 and 18—so far this year they’re up to 12. Saw-whet owl banding in this St. Louis County peaks in October; down there in that St. Louis County it peaks in November.

During banding, saw-whets get weighed and measured,
but they put up with it all pretty gracefully.
Photo by Pat Lueders.
Percentage-wise, very few banded birds of any species are ever reported again. The biggest rates of return tend to be in game species because so many ducks are harvested every year, and duck hunters are conscientious about reporting every banded bird that they shoot. But as owl banding stations have become better and better at catching saw-whets, and as more and more of these banding programs have started up, we’re seeing more returns. Even with relatively few owls caught so far at the World Bird Sanctuary, their owl-banding program has already had a few returns. In 2016, they recaptured one originally banded in Ontario. And one bird they banded in 2014 was recaptured this summer at Whitefish Point in Michigan.

Susan messaged me on Tuesday night as soon as she got home from banding because at 8:30, they'd caught a female saw-whet who was already bearing a band. It used to take weeks to trace a band number via the Patuxent Bird Banding Lab, but thanks to the miracle of the internet, it now takes moments. Susan already knew that this individual was banded on October 14, 2014, up here in Duluth!

Susan took this photo with her cell phone to send me.
It shows Frankie's spread wing illuminated by a black light.

This was the sixth owl they’ve caught this season. To make it fun and easy to keep the individuals straight, they give them informal names as well as band numbers; like hurricanes, the first bird caught gets a name that starts with A and they run through the alphabet. They’re calling this one Frankie for the granddaughter of Pat Lueders, one of the banders. Amusingly, just as this little owl gives us a St. Louis County connection, she also gives us a Frankie connection, because the Bird Banding Lab sent confirmation that the bander who originally banded her is Frank Nicoletti, the Research Director for Hawk Ridge Bird Observatory.

Most of the photos Susan sent me were taken by Pat Lueders while banding coordinator Linda Tossing held Frankie. One shows Frankie’s spread wing looking fluorescent pink. That photo was taken under the illumination of a black light.

Why is it pink? One of the pigments in a saw-whet owl’s feathers is porphyrin, a pigment our eyes can’t see without help because it’s visible only at the ultraviolet end of the spectrum. This pigment fades over time, most quickly when exposed to sunlight. Fresh new saw-whet feathers are rich in porphyrin, showing up to our eyes as a brilliant pink under a black light. Owls don't molt all their flight feathers every year but, rather, molt a few each year in a predictable pattern, so bird banders can distinguish which feathers are fresh and which are at least a year old by the pink color. Some of the primary and secondary wing feathers glow bright pink and some don't show much or any pink. All the covert feathers--the ones covering the bases of the flight feathers--are pink, because all those feathers are molted every year. (You can see the color pattern for owls of different ages here at the McGill University website.) 

Frankie's wing under black lights. Photo by Pat Lueders.
Understanding the predictable pattern of owl molt, banders can look at which primary and secondary feathers are bright pink and which aren’t to get a good estimate of the bird’s age. In 2014, Frank Nicoletti used Frankie’s molt stage to determine that she'd hatched in 2013. That makes her four years old now. Little by little these banding returns give us more and more information about how long birds live, and what their seasonal and geographic migration patterns are.

Owls don’t have access to black lights, but it’s hard to imagine that they produce a pigment that they themselves can’t see, especially since we already know that a lot birds see ultraviolet wavelengths. My guess is that owls probably use the intensity of the color to select the best potential mates. How would that help? Because the pigment degrades fastest when exposed to sunlight, the individuals most skilled at finding and defending daytime roosts would retain the most pigment. And who knows? Saw-whets may also use molt pattern the way bird banders do, to figure out how old a potential mate is. For most birds, the older a potential mate the better, because older birds have more experience and proven survival skills. We humans apparently know this intuitively—why else would the expression be “wise old owl” rather than “wise young owl”?

Frankie, photo by Pat Lueders